Device for flexible wideband frequency transposition, and associated satellite remote control receiver

Abstract

A device for double frequency transposition includes means for controlling the frequencies F OL1 , F OL2 of a first and a second synthesizer, which are adapted to carry out the steps of (a) initializing the frequency F OL2 at a first given value F OL2,A ; and (b) for a given pair of frequencies F RF , F FI2 , determining the frequency F OL1 with the aid of the following relations: if F RF >F OL1 and F FI1 <F OL2 , F RF =F OL1 +F OL2 −F FI2   (5), if F RF >F OL1 and F FI1 >F OL2 , F RF =F OL1 +F OL2 +F FI2   (6), if F RF <F OL1 and F FI1 >F OL2 , F RF =F OL1 −F OL2 −F FI2   (7), if F RF <F OL1 and F FI1 <F OL2 , F RF =F OL1 −F OL2 +F FI2   (8); and (c) if the value obtained for F OL1 lies in a frequency band of lower bound A·F REF −B·X and upper bound A·F REF +B·X, where A is a strictly positive integer and X is a given parameter, modifying the frequency F OL2 to a second value F OL2,B determined so that the difference in absolute value between F OL2,A and F OL2,B satisfies the following two conditions: | F OL2,B −F OL2,A |>AF REF +2 B·X | F OL2,B −F OL2,A |<AF REF −2 B·X; and (d) transmitting the frequency values F OL1 and F OL2 to said frequency synthesizers.

1. A device for double frequency transposition, comprising at least one first amplification and/or filtering chain receiving a signal at a first frequency F RF , a first frequency mixer which carries out a first frequency transposition of said signal to a first intermediate frequency F FI1  and delivers said transposed signal to the input of a second amplification and/or filtering chain, a second frequency mixer which carries out a second transposition of the signal delivered by said second chain to a second intermediate frequency F FI2  and delivers said transposed signal to the input of a third amplification and/or filtering chain, a first fractional frequency synthesizer of loop band B adapted to produce a first synthesized frequency F OL1  at the input of said first mixer and a second integer or fractional frequency synthesizer adapted to produce a second synthesized frequency F OL2  at the input of said second mixer, and further comprising means for controlling the frequencies F OL1 , F OL2  of said first and second synthesizers, which are adapted to carry out the following steps:
 initializing the frequency F OL2  at a first given value F OL2,A , 
 for a given pair of frequencies F RF , F FI2 , determining the frequency F OL1  with the aid of the following relations:
   if  F   RF   >F   OL1  and  F   FI1   <F   OL2   , F   RF   =F   OL1   +F   OL2   −F   FI2   (5),
 
   if  F   RF   >F   OL1  and  F   FI1   >F   OL2   , F   RF   =F   OL1   +F   OL2   +F   FI2   (6),
 
   if  F   RF   <F   OL1  and  F   FI1   >F   OL2   , F   RF   =F   OL1   −F   OL2   −F   FI2   (7),
 
   if  F   RF   <F   OL1  and  F   FI1   <F   OL2   , F   RF   =F   OL1   −F   OL2   +F   FI2   (8),
 
 
 if the value obtained for F OL1  lies in a frequency band of lower bound A·F REF −B·X and upper bound A·F REF +B·X, where A is a strictly positive integer and X is a given parameter, modifying the frequency F OL2  to a second value F OL2,B  determined so that the difference in absolute value between F OL2,A  and F OL2,B  satisfies the following two conditions:
   | F   OL2,B   −F   OL2,A   |>AF   REF +2 B·X    
   | F   OL2,B   −F   OL2,A   |<AF   REF −2 B·X  
 
 
 and 
 transmitting the frequency values F OL1  and F OL2  to said frequency synthesizers. 
 
     
     
       2. The double frequency transposition device as claimed in  claim 1 , wherein said means for controlling the frequencies F OL1 , F OL2  are adapted to carry out initially, for a set of given frequency pairs F RF , F FI2 , said calculation steps for determining the associated values of the frequencies F OL1 , F OL2  of said frequency synthesizers and to record the set of frequencies F RF , F FI2 , F OL1 , F OL2  obtained in a memory which they comprise. 
     
     
       3. The double frequency transposition device as claimed in  claim 2 , wherein said means for controlling the frequencies F OL1 , F OL2  are formed by an integrated circuit of the ASIC or FPGA type comprising at least one memory. 
     
     
       4. A remote control receiver for a geostationary satellite, comprising at least means for demodulating a signal at the intermediate frequency F FI2  and a double transposition device as claimed in  claim 1 , which receives a signal at the frequency F RF  and delivers said transposed signal at the intermediate frequency F FI2 .